1. Field of the Invention
The invention relates to a technique for controlling a storage system using a disk drive device having a self-check function.
2. Description of the Related Art
Storage systems employing disk drive devices have been used conventionally. Some disk drive devices have a self-check (self-test) function. A known example of this function (technology) is SMART (Self monitoring Analysis and Reporting Technology). This type of self-check function is used when a disk drive is replaced (See, for example, U.S. Patent Published Application No. 2004/0260967).
Spin-up-state is the basic operating state of many disk drive devices provided in conventional storage systems. Accordingly self checks scarcely cause spin up of disk drive devices. Recently, meanwhile, some storage systems have made use of MAID (Massive Array of Inactive Disks) technology. In MAID, at least part of the disk drive devices with no access among a plurality of disk drive devices is spun down. MAID can be used to reduce power consumption, increase storage system density (space saving), and increase the life of disk drive devices. Self checks are done repeatedly to ascertain the most recent state of disk drive devices. However, self checks add to the load on disk drive devices. Self checks may thus shorten the life of disk drive devices. Particularly in storage systems employing MAID technology, self checks are sometimes accompanied by spin up or spin down, which can thus impose a significant burden on disk drive devices.
These types of problems are not limited to spin up or spin down during self checks but are also common to self checks without spin up or spin down. Such problems are also not limited to storage systems in which some disk drives are spun down, such as MAID, but are also common to storage systems in which the disk drive devices are not spun down at all.